Won't power on, new ac contactor

D

Driveslayer45

Registered
Registered
Joined
Mar 5, 2019
Messages
216
Good evening all,

I have a similar model to a 9729 3 in 1 lathe, mill, drill. It shut itself off, lost power, for no apparent reason. The AC connector tripped, I guess. Anyway I looked the machine over for shorts, nicks in the wires, the usual stuff. Tested the ER switch and power on switch with a multi-meter, they checked out. If i manually engage the AC contactor the machine operates, so I purchased and installed a new ac contactor.

I hope someone can give me a suggestion.
 
Does the new contactor work or is it the new one you're having problems with?
 
No power getting to the contactor coil, sounds like. Need to trace that circuit. The coil could be 120 volt ac or some other voltage like 24, with a step down transformer somewhere
Could be a bad switch or a loose connection- is there a diagram for the machine?
Mark
 
The new contactor doesn't work either. The schematics for the grizzly match my machine, but they are fairly simple. I've checked the wires and connections to ensure they are tight, to no avail.
 
As Mark mentioned, you need to check that the contactor solenoid is getting power. Do you see any fuse blocks? Maybe a blown fuse.
 
The 9729 diagram is very simple. There are several switches in series with the coil, including a microswitch. By the way is the emergency stop switch pulled out? Is the microswitch jammed up ? (I believe it's the safety cover switch) make sure you can hear it clicking
Try jumpering the switches one at a time, starting with the microswitch if none of the above works
be careful
 
Last edited:
We had a similar issue at work the other day. Contactors have a thermal overload on the control side (sometimes called "the heater"). If you can push the contactor closed manually, and the spindle runs, the problem is on the control side not the power side. In our case all the overloads were in series, so when one dropped it took everything down - pumps, spindle, fast traverse, etc. We tried a new contactor also - not. Checked the overloads until we found the open one, got it reset and everything worked. Contactors seem to work about the same so the instructions for the new one may help with the old one.
 
Thanks for all the help. I found the issue. There is a safety switch on the cover of the mill.. when you screw the cover down it disengages the safety, let's power through. That switch failed... Pulled my hair out chasing wires as that switch was not on the wiring diagram
 
manually pushing in the contactor is the simplest test to see if there is a problem in the control circuit or the contactor.

if you push in on the contactor, and the machine runs, you then know the problem lies in the control circuit
if you push the contactor and it doesn't run, you know there is a problem with the contactor, or incoming power
 
You must log in or register to reply here.
Back
Top